While usage is low, it's not quite the ghost town some claim, and there's a deeper story behind the numbers

Google entered the social networking game with Google+ to fanfare and high hopes. But only a third of the site's users ever make a public post, and those who do only post every 12 days.

Google+ seems to be inescapable. Everywhere you go on the Web, you see that little logo and a picture. (Heck, I get tired of seeing my own mug staring back at me, page after page.) And people who are responsible for traffic on many sites have worried that competitors will find ways to use the social networking feature to grab page views.

Fears and annoyance aside, it turns out that Google+ is not nearly as popular as Google had hoped and many had feared. That's not to say, as some commentators have gleefully reported, that it's a "ghost town." It is not. The truth is more nuanced and tells us something important about the way the Web works these days.

Although Google says that plus has more than 100 million users, a survey by RJ Metrics cast serious doubt on how engaged those users really are. Indeed, it appears that only one third of the users ever post publicly, many only post a few times, and even then, at fairly wide intervals. "It looks like there is a large dormant user population that may have joined as result of being opted in by other Google services," says Robert J. Moore, CEO of the business analytics company.

That sounds pretty bleak, and it does seem likely that Google overestimated the enthusiasm for yet another social network. But there's something important to keep in mind. Google+ users can post privately, as well as publicly, and when they do so, the engine used by RJ Metrics cannot see them, Moore says.

It's also evident that because many people opt in as part of their interaction with another Google service, those casual users who don't have much interest in the service will pull down the averages of time spent on the site and time between posts and so on, he tells me. (Moore, by the way, deserves some respect for being so frank about the limitations of his research instead of simply hyping it, as some analyst firms tend to do.)

Google+: Public engagement is very lowRJ Metrics sampled posts by 40,000 randomly selected users. For each user who had actually posted (about one third of the sample), the company downloaded their entire public timelines, which consist of all of their publicly visible activities.

Here's what they found:

The average post has less than one +1, less than one reply, and less than one re-share.

30 percent of users who make a public post never make a second one. Even after making five public posts, there is a 15 percent chance that a user will not post publicly again.

Among users who make publicly viewable posts, there is an average of 12 days between each post.

After a member makes a public post, the average number of public posts he or she makes in each subsequent month declines steadily.

Not surprisingly, Google disputes the findings of the RJ Metrics study, and in a statement to Fast Company, which wrote about the research last week, the company said, "By only tracking engagement on public posts, this study is flawed and not an accurate representation of all the sharing and activity taking place on Google+.... As we've said before, more sharing occurs privately to circles and individuals than publicly on Google+. The beauty of Google+ is that it allows you to share privately -- you don't have to publicly share your thoughts, photos, or videos with the world."

Google+ usage: Just three minutes a monthAs Moore himself points out, there's no way to know how many posts are shared privately. But there's another metric, one that wasn't used by RJ Metrics, that is probably even more distressing from Google's point of view: Time using the service.

In February, ComScore found that visitors using personal computers spent an average of about three minutes a month on Google+ between September and January, versus six to seven hours on Facebook each month over the same period. Google says that ComScore data understates the amount of time people spend on the service, but did not share its own numbers.

It's possible that Google+ is a different kind of animal, one whose popularity researchers haven't been able to capture. But I suspect that we're seeing three things:

Many people aren't exactly sure what Google+ really is about. It's not search, it's not Facebook, it's not Twitter, so what is it?

Facebook may have such a huge advantage in the marketplace that it's game over, at least for now, for Zuckerberg wannabes.

Given the poor performance of Facebook’s stock during its first few trading sessions, there may well be a glut of social media. Or maybe, just maybe, people are tiring of so much sharing and are starting to see the virtue in a bit of privacy.

I welcome your comments, tips, and suggestions. Post them here (Add a comment) so that all our readers can share them, or reach me at bill@billsnyder.biz. Follow me on Twitter at BSnyderSF.

San Francisco journalist Bill Snyder writes frequently about business and technology. He writes the Tech's Bottom Line blog for InfoWorld, and his work appears regularly in CIO.com and the publications of Stanford's Graduate School of Business and the Haas School of Business at the University of California at Berkeley.